1. Field of Art
The present invention relates to cooling equipment for an excavator.
2. Description of Prior Art
As known in the art, an excavator is provided, among other things, with cooling equipment designed for lowering the temperature of one or more coolant liquids set in circulation to and from the mechanical members that generate thermal energy.
Such cooling equipment comprises, in general, an air intake, an air-delivery duct to one or more devices (such as radiators) for the cooling of fluids (coolant water, air, hydraulic oil, etc.), and a fan operable to send a flow of ambient air from the air intake towards the cooling devices, through the delivery duct, for providing the desired cooling on the fluids.
As an example, in the past, a first solution has been proposed, in which the air intake is located laterally on the bonnet of the excavator. In this case, the radiator is set directly facing the air intake.
The major advantage of this solution is essentially the fact that the dimensions of the radiator are not linked to other dimensional characteristics of the excavator (such as the width thereof in a direction transverse to the direction of movement), so that the manufacturer can decide, with a certain degree of freedom, the overall dimensions of the excavator itself. In addition, the above configuration results in a lower noise level of the cooling system as observed in the cab of the vehicle, since the noise is emitted in a lateral direction, away from the cab.
On the other hand, the drawbacks of this first solution of the prior art are due fundamentally to the fact that the flow of air, under conditions when the excavator is moving, is directed parallel to the face of the radiator. As a result, there is not an optimal use of the motion of the motor vehicle itself for a complementary cooling of the radiator; a complementary cooling which is otherwise to be added to the cooling obtained by means of the forced flow of air generated by the fan. This is all the worse since a moving excavator requires a power which is clearly higher than the power required under normal stationary working conditions, above all when it involves an excavator mounted on wheels and not on tracks.
Some calculations, which are backed up by corresponding experiments, have indicated that the operations of stationary digging with the excavator require only approximately 70% of the power that is necessary when the same excavator is moving. This means that, as has been mentioned, during movement, the radiator is required to dissipate more heat than is necessary under stationary working conditions.
Consequently, with the first solution previously illustrated, in critical conditions it is necessary to increase the speed of the fan. However, such an increase is possible only up to a certain limit, since there are constraints due to the maximum operating speed of the engine to which the fan is connected and to the coupling between the engine shaft and the fan shaft. Alternatively, it would be possible to open the bonnet in front of the radiator so as to allow unobstructed passage of air and thus to increase the air flow for cooling purposes. However, opening of the bonnet is not desirable because in this way the noise produced by the cooling equipment increases considerably. Moreover, this would result in an increase of the amount of dust that would deposit on the outer surface of the radiator itself, with readily imaginable undesirable effects.
Conversely, in a second known solution, the air intakes are set on the front part of the vehicle bodywork, oriented in the direction of normal travel. Also in this case the radiator is set facing the air intakes.
This second solution has the evident advantage that, in the conditions in which the excavator requires maximum dissipation of thermal energy, i.e., when the excavator is moving, this dissipation is facilitated by the motion of the vehicle itself.
However, in this second embodiment of the known art, the radiator is located very close to the cab in which the driver sits, and moreover it receives the flow of air hit-on, which further increases the noise level. Furthermore, since both the air intakes and the radiator are located alongside the arm of the excavator, when the latter is in working conditions, there is consequently an increase in the deposit of dust on the outer surface of the radiator. This results in a layer of dust which considerably reduces heat exchange between the forced flow of air and the liquid passing through the radiator.
The purpose of the present invention is therefore to provide cooling equipment for motor vehicles, in particular for excavators, that are exempt from the drawbacks described above.
Consequently, according to the present invention cooling equipment is provided for motor vehicles according to the characteristics claimed in claim 1.